Create a Custom Exception

    export class ForbiddenException extends HttpException {
        constructor() {
            super('Forbidden', HttpStatus.FORBIDDEN);
        }
    }

• In many cases, you will not need to write custom exceptions, and can use the built-in Nest HTTP exception.
• If you do need to create customized exceptions, it's good practice to create your own exceptions hierarchy, where your custom exceptions inherit from the base HttpException class.
• With this approach, Nest will recognize your exceptions, and automatically take care of the error responses.

CatsController

    @Get()
    async findAll() {
        throw new ForbiddenException();
    }